Oral Cavity & Palate PDF

Oral Cavity & Palate DPM Program Learning Objectives 1. Describe the functional anatomy of the tongue, including its motor and sensory (general and special) innervations. 3.0 2. Describe the neurovasculature of the oral cavity. 3.0 3. Describe the major salivary glands. 3.0 4. Discuss the roles of t...

Oral Cavity & Palate DPM Program Learning Objectives 1. Describe the functional anatomy of the tongue, including its motor and sensory (general and special) innervations. 3.0 2. Describe the neurovasculature of the oral cavity. 3.0 3. Describe the major salivary glands. 3.0 4. Discuss the roles of the submandibular ganglion. 3.0 5. Explain the spread of infections from the oral cavity into the neck. 3.0 1 The Palate 2 The Oral Cavity 2 parts: i) oral vestibule, between the teeth and cheeks/ lips ii) oral cavity proper, between upper and lower dental arcades bounded superiorly by the hard and soft palates runs as far posteriorly as the palatoglossal folds. The palate: Hard palate -anterior two-thirds -palatine process of maxilla and horizontal plates of palatine bones -has incisive, greater and lesser palatine foramina Soft palate – movable, posterior one-third of palate -strengthened by the expanded tendon of tensor veli palatini (palatine aponeurosis) -composed of five muscles covered by mucosa: -musculus uvulae -tensor veli palatini (V3) -levator veli palatini -palatoglossus - palatopharyngeus 3 Muscles of the Soft Palate Tensor veli palatini (V3) - Forms ‘skeleton’ of the soft palate/ tenses palate: opens auditory tube when swallowing Palatoglossus - Elevates tongue Levator veli palatini - Elevates palate Palatopharyngeus - Elevates pharynx Muscles of the soft palate are all innervated by Vagus (CNX), except for tensor veli palatini which is innervated by the Mandibular division of Trigeminal (CNV3) 4 The Tongue The tongue is a muscular structure that forms part of the floor of the oral cavity. The oral cavity has a hard palate and a soft palate. Body=anterior two-thirds Root=posterior one-third (these are separated by the terminal sulcus whose apex is defined by the foramen cecum) Tongue Muscles (all muscles innervated by the hypoglossal nerve (CN XII) except for Palatoglossus which is innervated by vagus nerve (CN X) : Extrinsic muscles originate from structures outside the tongue and insert into the tongue. These muscles protrude, retract, depress, and elevate the tongue. Alter the position of the tongue. These muscles are: 1) Genioglossus (Asking a patient to “stick your tongue out” can be used as a test for the hypoglossal nerves [XII]. If the nerves are functioning normally, the tongue should protrude evenly in the midline. If the nerve on one side is not fully functional, the tip of the tongue will point to that side.) 2) Hyoglossus 3) Styloglossus 4)Palatoglossus Intrinsic muscles: Working in pairs or one side at a time contribute to precision movements of the tongue required for speech, eating, and swallowing. Alter the shape of the tongue. Innervation: GSE (motor) – Hypoglossal (except for palatoglossus (CN X)) Ant. 2/3: -GSA (sensory) – lingual (V3) -SA – chorda tympani (VII) Post 1/3 (including vallate papillae): -GSA – Glossopharyngeal (IX) (some internal laryngeal nerve (CN X)) -SA – Glossopharyngeal (IX) (some internal laryngeal nerve (CN X)) 5 The Tongue 6 Muscles of the Tongue TONGUE MUSCLES Intrinsic – alter the shape of the tongue Extrinsic – alter the position of the tongue Palatoglossus Styloglossus Hyoglossus Genioglossus Mylohyoid Geniohyoid 7 Salivary Glands Lingual nerve -passes lateral to, then inferior to, then medial to submandibular duct -passes up to anterior twothirds of tongue Sublingual gland -drains by several small ducts into the sublingual folds in floor of mouth Submandibular (Wharton’s duct) Submandibular gland -originated from submandibular salivary gland -runs superior to mylohyoid m., deep to sublingual gland 8 Innervation: GSE (motor) – Hypoglossal (except for palatoglossus (CN X)) Ant. 2/3 -GSA (sensory) – lingual (V3) -SA – chorda tympani (VII) Post 1/3 (including vallate papillae): -GSA – Glossopharyngeal (IX) (some internal laryngeal nerve (CN X)) -SA – Glossopharyngeal (IX) (some internal laryngeal nerve (CN X)) 9 Neurovasculature of the Palate GVE: -glands of the palate receive parasympathetic innervation from CN V2 (via the pterygopalatine ganglion) & sympathetic innervation from the deep petrosal nerve SA: -Taste from the palate is from CN VII SOMATIC: -GSA to the palate is primarily from the greater & lesser palatine nerves (V2) -GSE to the soft palate is from the pharyngeal plexus (CN X) (except for tensor veli palatini m. which is innervated by V3) BLOOD SUPPLY: - the majority of blood supply to the palate comes from the greater and lesser palatine arteries (off the descending palatine from the Maxillary artery) 10 Neurovasculature of the Oral Cavity Blood supply to the floor of the oral cavity and tongue is primarily from the lingual artery (from ECA). Venous drainage is from deep and dorsal lingual vv. (both of which drain to the IJV) 11 Parasympathetic Innervation of the Submandibular and Sublingual Salivary Glands Preganglionic parasympathetic nerve cell bodies are located in the superior salivatory nucleus (Pons) and their fibers leave the brain stem in the nervus intermedius portion of the Facial Nerve (CN VII). These fibers are carried to the infratemporal fossa in the chorda tympani nerve which joins the lingual nerve. The preganglionics are then carried (which are now in the lingual nerve) to the submandibular ganglion (located close to the posterior border of the mylohyoid muscle in the submandibular triangle) where they terminate by synapsing with the cell bodies of the postganglionic parasympathetic neurons. The postganglionic parasympathetic fibers then leave the ganglion and pass directly to the sublingual and submandibular salivary glands. 12 The Submandibular Ganglion -PARASYMPATHETIC INNERVATION TO THE ORAL SALIVARY GLANDS 13 Cranial Nerve Testing for Hypoglossal Nerve A lesion of the hypoglossal nerve (CN XII) will cause the tongue to deviate TOWARD the injured side due to paralysis of the ipsilateral genioglossus muscle. 14 Tongue Development 1st pharyngeal arch forms anterior 2/3 of tongue (sensation via CN V3, taste via CN VII. 3rd and 4th pharyngeal arches form posterior 1/3 of tongue (sensation and taste mainly via CN IX, extreme posterior via CN X). Motor innervation is via CN XII to hyoglossus (retracts and depresses tongue), genioglossus (protrudes tongue), and styloglossus (draws sides of tongue upward to create a rough trough for swallowing). Motor innervation is via CN X to palatoglossus (elevates posterior tongue during swallowing) 15